In the aftermath of Sep. 11, 2001, mobile robots have been used for USAR (Urban Search and Rescue) activities such as searching for victims, searching paths through the rubble that would be quicker than to excavate, structural inspection and detection of hazardous materials. Among the few mobile robots that were used such as the Inuktun's Micro-Tracs™ and VGTV™ and Foster-Miller's Solem™ and Talon™, the capability was very limited in terms of locomotion and mobility. The capabilities are further limited if one considers any requirements of manipulation with an arm mounted on the mobile robot, and because of these limitations in many instances the robotic arm was not used at all. Some of the most serious problems with the robots were the robot flipping over or getting blocked by rubbles into a position from where it could not be righted or moved at all. None of the robots used on the rubble pile searches were successfully inverted after flipping over. These are only some of the several outstanding problems among the many challenges that are still encountered in the field of small Mobile Robots for Unmanned Ground Vehicle (UGV) operations for rough terrain applications.
Increasingly, mobile robotic platforms are being proposed for use in rough terrain and high-risk missions for law enforcement and military applications (e.g., Iraq for IEDs—Improvised Explosive Devices), hazardous site clean-ups, and planetary explorations (e.g., Mars Rover). These missions require mobile robots to perform difficult locomotion and dexterous manipulation tasks. During the execution of such operations loss of wheel traction, leading to entrapment, and loss of stability, leading to flip-over, may occur. These events often result in total mission failure.
Various robot designs with actively controlled traction, sometimes called “articulated tracks”, were found to somewhat improve rough-terrain mobility, but with limited capability to reposition the mobile robot center of gravity (COG). The repositioning of COG allows a certain degree of control over the robot stability. Efforts are continuously made in designing robots that allow a wider control over COG location providing greater stability over rough terrains. This is achieved by designing robots with displacing mechanisms and actively articulated suspensions that allow for wider repositioning of the COG in real-time. However, the implementations of such solutions most often result in complex and cumbersome designs that significantly reduce robot's operational reliability, and also increase its cost.
There are numerous designs of mobile robots such as PackBot™, Remotec-Andros™ robots, Wheelbarrow MK8™, AZIMUT™, LMA™, Matilda™, MURV-100™, Helios-II™, Variable configuration VCTV™, Ratler™, MR-1™, MR-5™ and MR-7™, NUGV™, and Talon™ by Foster Miller. They are mainly based on wheel mechanisms, track mechanisms and the combination of both. As well, some legged robots have been suggested for rough terrain use. However, all of these robots have certain limitations. Specifically they have difficulty getting out of certain situations such as if they become inverted.
A review of several leading existing mobile robot designs has indicated that it would be advantageous to provide a mobile robot wherein each kinematic link has multiple functions. Further it would be advantageous to provide a mobile robot that is invertible. Similarly it would be advantageous to provide an invertible mobile robot with an arm integrated into the platform. Still further, it would be advantageous to provide a mobile robot that has a tension and suspension system. One aim is to increase the robot's functionality while significantly reducing its complexity and hence drastically reducing its cost.